1
dc1649afa
DEMO MANUAL DC1649A
DESCRIPTION
LTC6945
Ultralow Noise and Spurious
Integer-N Synthesizer
Demonstration circuit 1649A features the LTC
®
6945, an
ultralow noise and spurious integer-N synthesizer.
DC1649A provides 50Ω SMA connectors for the reference
frequency (REF+), the reference output buffer (REFO),
and the two single-ended RF outputs (RF+ and RF–). L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
PLLWizard and QuikEval are trademarks of Linear Technology Corporation. All other trademarks
are the property of their respective owners.
Demonstration circuit 590 is used for SPI communication
with the LTC6945, controlled by the supplied PLLWizard™
software.
Design files for this circuit board are available at
http://www.linear.com/demo
Figure 1. DC1649A Inputs and Outputs
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dc1649afa
DEMO MANUAL DC1649A
TYPICAL DC1649A REQUIREMENTS AND CHARACTERISTICS
QUICK START PROCEDURE
PARAMETER INPUT OR OUTPUT PHYSICAL LOCATION DETAILS
3.3V Power Supply Input J9 and J10 Banana Jacks Low Noise and Spur-Free 3.3V, 95mA
5V Charge Pump Power Supply Input J11 and J12 Banana Jacks Low Noise and Spur-Free 5V, 35mA
5V VCO Power Supply Input “V+VCO” Turret Low Noise and Spur-Free 5V, 18mA
REF+, Reference Frequency Input J2 SMA Connector Low Noise 10MHz or 100MHz*, 6dBm into
50Ω, See Note 1
REFO, Buffered Reference Output J1 SMA Connector Frequency = fREF, 0dBm
RF+ and RF– Two Outputs J6 and J7 SMA Connectors 902MHz to 928MHz* in 250kHz* Steps, 0dBm
Loop Bandwidth Set by Loop Filter Component Values 7kHz*
*These frequencies are for the “DC1649A-10MHz.pllset “or” DC1649A-100MHz.pllset” files and included VCO.
Note 1: A low noise 10MHz or 100MHz reference frequency, such as the
Wenzel 501-04608A or 501-04516D OCXO, is recommended. If using a
different frequency, make sure to update the Fref and R_DIV boxes under
the System tab in PLLWizard so that Fpfd is still 250kHz. For example, if a
20MHz clock is used, Fref should be changed to 20MHz and R_DIV to 80.
Ref BST and FILT under the System tab in PLLWizard might need to be
changed if the reference frequency and/or power is different than what is
recommended in the table above. More information can be found in the
LTC6945 data sheet.
The DC590 and PLLWizard application are required to
control the DC1649A through a personal computer (PC).
DC590B Configuration
The DC590’s QuikEval™ drivers must be installed before
the DC590 will be able to communicate with the LTC6945.
To configure the DC590, follow the procedure below, start-
ing with Step 1. If you have already installed the DC590
software previously, skip to Step 5.
Note: Once the QuikEval software is installed, the applica-
tion Does Not need to be executed to run PLLWizard or to
control the DC1649A.
1. Do Not plug in the DC590 before running the installation
program.
2. Download the QuikEval installation program from
http://www.linear.com/software.
3. Run the QuikEval installation program and follow the
on-screen instructions. More detailed installation infor-
mation may be found in the DC590’s Quick Start guide.
4. Exit the QuikEval program once the installation is com-
plete, as it is not needed to run the PLLWizard software.
5. Place the DC590 jumpers in the following positions:
JP4 - EE Must be in the “EN” position.
JP5 - ISO ”ON” must be selected.
JP5 - SW ”ON” must be selected.
JP6 - VCCIO “3.3V” must be selected. This sets the SPI
port to 3.3V operation.
6. Connect the DC590 to one of your computer’s USB
ports with the included USB cable.
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dc1649afa
DEMO MANUAL DC1649A
QUICK START PROCEDURE
Figure 2. DC590 Jumper and Connector Locations
PLLWizard Installation
The PLLWizard software is used to communicate with
the LTC6945 synthesizer. It uses the DC590 to translate
between USB and SPI-compatible serial communications
formats. It also includes advanced PLL design and simula-
tion capabilities. The following are the PLLWizard system
requirements:
n Windows Operating System: Windows XP, Windows
2003 Server, Windows Vista, Windows 7
n Microsoft .NET 2.0 or later
n Windows Installer 3.1 or later
n Linear Technology’s QuikEval and DC590 hardware
Microsoft .NET
You must have Microsoft .NET 2.0 or later installed on
your computer. PLLWizard will not run without it. Note
that Windows Vista and Windows 7 have at least version
3.5 preinstalled.
To manually determine your version of .NET using Win-
dows XP, click
Start Menu → Settings → Control Panel → Add or
Remove Programs
Depending upon your .NET version, choose one of
two PLLWizard setup programs, downloaded from
http://www.linear.com/software.
Either setup program will automatically install Microsoft
.NET if a compatible .NET version is not found. But, the
installation source depends upon which file you down-
loaded from Linear Technology’s website. You should pick
one of the following two choices, depending upon your
version of .NET.
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dc1649afa
DEMO MANUAL DC1649A
QUICK START PROCEDURE
Table 1. PLLWizard Installation File
FILE .NET 2.0 SOURCE
PLLWizardSetup.exe latest version downloaded from
Microsoft
PLLWizardSetup_net20.exe 2.0 SP2 included (much larger file size)
n Choose PLLWizardSetup if you have .NET 2.0 or later,
have Windows Vista or Windows 7, or if you have less
than .NET 2.0 but want the latest .NET installed.
n Choose PLLWizardSetup_net20 if you have less than
.NET 2.0, and want faster installation (no additional
Microsoft downloads are needed, but the file size is
much larger).
The setup file will verify and/or install Microsoft .NET and
install PLLWizard. Refer to the Help menu for software
operation.
DC1649A Configuration
1. Connect an appropriate reference frequency source (at
J2) and signal analyzers (at J6 and/or J7) using the
SMA connectors (see Figure 1 and the Typical DC1649A
Requirements and Characteristics table).
2. Choose the MUTE jumper setting: JP1 - GND/3.3V MUTE
position. Select GND to mute the RF output, 3.3V to
un-mute.
3. Connect the GND, 3.3V, and 5V banana jacks and the
“V+VCO” turret to a power supply and apply power (see
Figure 1 and the Typical DC1649A Requirements and
Characteristics table).
4. Connect the DC590 to the DC1649A with the provided
ribbon cable.
5. Run the PLLWizard application.
6. In PLLWizard, click File → Load Settings and point to the
“DC1649A-10MHz.pllset” or “DC1649A-100MHz.pllset”
file found in the PLLWizard installation directory (typically
Program Files → LTC → PLLWizard → Set Files).
The red LED on DC1649A should turn on indicating that
the loop is locked at 914MHz.
Troubleshooting
If the red LED does not illuminate, follow the instructions
below:
1. Verify that you are able to communicate with the
DC1649A. The bottom status line in PLLWizard should
read “LTC6945” and “Comm Enabled”. Refer to PLL-
Wizard’s Troubleshoot and Help if not.
2. Verify that the 3.3V, 5V and “V+VCO” have the correct
voltages on them and that the reference frequency is
applied to the REF+ SMA input.
If the red LED is on but you cannot detect an RF out-
put, make sure jumper JP1 is at the 3.3V position. Run
Help → Troubleshoot in PLLWizard if the problem is not
resolved.
Figure 3. PLLWizard Screenshot
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DEMO MANUAL DC1649A
DC1649A RECONFIGURATION
DC1649A is flexible and allows the use of a variety of VCOs
and the choice to employ either an active or passive loop
filter. The following covers the hardware reconfiguration of
DC1649A. Refer to PLLWizard’s Help and the LTC6945 data
sheet to better understand how to change programmed
parameters on the DC1649A.
Installing Different Tunable Devices
DC1649A permits the use of different tunable oscillators,
like VCOs and VCXOs. There are two different oscillator
footprints on the board: U3, which accommodates the
popular 0.5in × 0.5in package, and U4, which accom-
modates another common 14mm × 9mm package with
four or six pins. An external connectorized VCO can also
drive the LTC6945 through J5. Table 2 gives options to
customize the DC1649’s VCOs. When using an active loop
filter, an additional pole is required in the loop filter to limit
the op amp’s noise contribution to the VCO phase noise.
Selecting Loop Filter Type
DC1649A can use either an active or a passive loop filter,
depending upon the application. Some VCO tuning volt-
age ranges are greater than the LTC6945 charge pump
voltage range (refer to the LTC6945 data sheet). In such
cases, an active loop filter using an op amp can deliver
the required tuning voltage. Table 3 summarizes these op-
tions. PLLWizard helps determine the component values
listed in this table.
Table 2. Oscillator Options
TUNABLE
DEVICE
SELECTION
COMPONENTS
RESISTOR FOR
ADDITIONAL POLE
CAPACITOR FOR
ADDITIONAL POLE POWER
ENABLE PIN OR
REMARKS
U3 C26 ≅ 100pF, depopulate
R17, C25 and C28
R10 = 0Ω for passive
loop filter
R10 ≅ 100Ω for active
loop filter
C27 = Open for passive
loop filter
Pick C27 such that
1/(2π • R10 • C27) ≅ 15 •
the loop bandwidth in Hz
for active loop filter
Determined by U3
device power supply
specification, up to 24V
applied to “V+VCO” turret
U4 C28 ≅ 100pF, depopulate
R10, C25 and C26
R17 = 0Ω for passive
loop filter
R17 ≅ 100Ω for active
loop filter
C32 = Open for passive
loop filter
Pick C32 such that
1/(2π • R17 • C32) ≅ 15 •
the loop bandwidth in Hz
for active loop filter
Determined by U4
device power supply
specification, up to 24V
applied to “V+VCXO”
turret
Use “EN” turret to control
pin 2 of U4
External C25 ≅ 100pF, R15 = 0Ω,
depopulate R13, C26
and C28
Selection components
are for an active loop
filter. Connect the external
VCO output to J5. Use
“CPGAIN” to tune the
external device
Table 3. Loop Filter Options
LOOP FILTER
TYPE
SELECTION
RESISTORS
RZ FROM
PLLWizard
CI FROM
PLLWizard
CP FROM
PLLWizard POWER
CPINV BOX, SYSTEM
TAB IN PLLWizard
Passive R14 and R16 = 0Ω,
depopulate R13 and
R15
RZ_P CI1_P in parallel
with CI2_P
CP_P None Unchecked
Active R13 (except when
using an external
VCO) and R15 = 0Ω,
depopulate R14 and
R16
RZ_A CI1_A in parallel
with CI2_A
CP_A Determined by the
maximum allowed
tune voltage of the
populated VCO (U3
or U4), up to 24V
applied to “V+OA”
turret
Checked
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DEMO MANUAL DC1649A
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
1 0 CI1_P, CI1_A, C27, C32, CP_A Opt., 0603
2 0 CI2_A Opt., 1206
3 1 CI2_P Cap., C0G, 0.1μF, 50V, 5%, 1206 Murata, GRM31C5C1H104JA01L
4 1 CP_P Cap., X7R, 8200pF, 50V, 10%, 0603 Murata, GRM188R71H822KA01D
5 3 C1, C19, C33 Cap., Tantalum, 47μF, 35V, 10%, 7361 AVX, TAJV476K035RNJ
6 4 C2, C6, C21, C35 Cap., X7R, 0.1μF, 50V, 10%, 0805 AVX, 08055C104KAT2A
7 2 C3, C16 Cap., Tantalum, 330μF, 10V, 10%,7343 AVX, TPME337K010R0035
8 10 C4, C11, C17, C24, C30, C36, C39,
C41, C43, C44
Cap., X5R, 0.1μF, 10V, 10%, 0402 AVX, 0402ZD104KAT2A
9 4 C5, C12, C18, C31 Cap., X5R, 1μF, 10V, 10%, 0402 AVX, 0402ZD105KAT2A
10 1 C7 Cap., Tantalum, 47μF, 20V, 10%, 7343 AVX, TAJD476K020RNJ
11 2 C8, C15 Cap., X7R, 470pF, 50V, 10%, 0402 AVX, 04025C471KAT2A
12 3 C23, C34, C45 Cap., X7R, 0.01μF, 16V, 10%, 0402 AVX, 0402YC103KAT2A
13 0 C25, C28 Opt., 0402
14 5 C26, C29, C37, C38, C42 Cap., NPO, 100pF, 16V, 10%, 0402 AVX, 0402YA101KAT2A
15 1 D1 LED, RED Panasonic, LN1251CTR
16 10 E3, E6, E11-E18 Turret, Testpoint, 2501 Mill-Max, 2501-2-00-80-00-00-07-0
17 1 JP1 Headers, 3 Pins, 2mm Ctrs. Samtec, TMM-103-02-L-S
18 1 XJP1 Shunt, 2mm Ctrs. Samtec, 2SN-BK-G
19 5 J1, J2, J5, J6, J7 Con., SMA 50Ω Edge-Launch E. F. Johnson, 142-0701-851
20 0 J3, J4 Con., SMA 50Ω Straight Mount Opt.
21 1 J8 Con., Header, 14 Pin, 2mm Molex, 87831-1420
22 4 J9, J10, J11, J12 Jack, Banana Keystone, 575-4
23 0 L1 Opt., 0402
24 2 L2, L3 Ind., Wirebound, 68nH, ±5%, 0402 Coilcraft, 0402HPH-68NXJL
25 1 RZ_P Res., Chip, 806, 1/10W, 1%, 0603 Vishay, CRCW0603806RFKEA
26 5 R1, R2, R25, R26, R27 Res., Chip, 4.99k, 1/16W, 1%, 0402 Vishay, CRCW04024K99FKED
27 1 R4 Res., Chip, 330, 1/16W, 1%, 0402 Vishay, CRCW0402330RFKED
28 1 R5 Res., Chip, 51.1, 1/16W, 1%, 0402 Vishay, CRCW040251R1FKED
29 4 R7, R8, R18, R19 Res., Chip, 200k, 1/16W, 1%, 0402 Vishay, CRCW0402200KFKED
30 4 R9, R10, R14, R16 Res., Chip, 0Ω, 0603 Vishay, CRCW06030000Z0EA
31 3 R12, R21, R22 Res., Chip, 100, 1/16W, 1%, 0402 Vishay, CRCW0402100RFKED
32 0 R13, R15, R17, RZ_A Opt., 0603
33 0 R23, R24 Res., Chip, 0402, Opt.
34 1 U1 I.C. LTC6945IUFD, QFN28UFD Linear Technology Corp., LTC6945IUFD
35 1 U2 Low Noise Amp, S0-8 Linear Technology Corp., LT1678CS8#PBF
36 1 U3 (1 Reel + 1 Tape, PbF) Voltage Controlled Oscillator – VC0 Crystek, CVCO55CL-0902-0928
37 0 U4 Crystal Oscillator, Opt.
38 2 U5, U6 I.C., Dual Buffer, SC-70 6-Lead Fairchild Semi., NC7WZ17P6X
39 1 U7 I.C., Dual Transceiver, SC-70 6-Lead NXP, 74LVC1T45GW
40 1 U8 I.C., Serial EEPROM, TSSOP-8 Mircochip, 24LC24A-I/ST
41 4 4 Corners Standoff, Nylon, 0.50, 1/2" Keystone, 8833 (Snap On)
42 2 Stencils (Top and Bottom) Stencil, DC1649A-4
PARTS LIST
Number of Boards = 325
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dc1649afa
DEMO MANUAL DC1649A
SCHEMATIC DIAGRAM
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
A A
B B
C C
D D
NOTE: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTORS ARE IN OHMS, 0402
ALL CAPACITORS ARE IN MICROFARADS, 0402.
3.3V
GND
0805 7343
MUTE
7343
VCO
902 - 928 MHz
ASSY U3
*
-A CVCO55CL-0902-0928
*
3.3V
3.3V
3.3V
3.3V
3.3V 3.3V
5V
V+VCO
V+VCXO
3.3V
V+VCO
3.3V
V+OA
5V
5V
CS
SCLK
SDO
SDI
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
MICHEL A.PRODUCTION4 11-01-11
__
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
MICHEL A.PRODUCTION4 11-01-11
__
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
MICHEL A.PRODUCTION4 11-01-11
__
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
4
11/01/2011, 02:18 PM
12
ULTRALOW NOISE AND SPURIOUS INTEGER-N SYNTHESIZER
KIM T.
MICHEL A.
N/A
LTC6945IUFD
DEMO CIRCUIT 1649A
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
4
11/01/2011, 02:18 PM
12
ULTRALOW NOISE AND SPURIOUS INTEGER-N SYNTHESIZER
KIM T.
MICHEL A.
N/A
LTC6945IUFD
DEMO CIRCUIT 1649A
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
4
11/01/2011, 02:18 PM
12
ULTRALOW NOISE AND SPURIOUS INTEGER-N SYNTHESIZER
KIM T.
MICHEL A.
N/A
LTC6945IUFD
DEMO CIRCUIT 1649A
E18 EN
E18 EN
C32
OPT
0603
C32
OPT
0603
C27
OPT
0603
C27
OPT
0603
+
C16
330uF
10V
+
C16
330uF
10V
R14 0
0603
R14 0
0603
JP1JP1
R16
0
0603
R16
0
0603
E12 CPGAIN
E12 CPGAIN
C31 1.0uF
C31 1.0uF
J12 GND
J12 GND
C23
0.01uF
C23
0.01uF
C15 470pFC15 470pF
J7
RF- J7
RF-
+
C33 35V
47uF
7361
+
C33 35V
47uF
7361
RZ_P
806
0603
RZ_P
806
0603
C5
1.0uF
C5
1.0uF
J3
CP
OPT J3
CP
OPT
C8
470pF
C8
470pF C17
0.1uF
C17
0.1uF
R1
4.99K
R1
4.99K
C2
0.1uF 0805
C2
0.1uF 0805
C45
0.01uF
C45
0.01uF
E13 V+VCO
E13 V+VCO
C12
1.0uF
C12
1.0uF
C11
0.1uF
C11
0.1uF J4 CPGAIN
OPTJ4 CPGAIN
OPT
CI2_A OPT
1206
CI2_A OPT
1206
J5 EXT VCO IN
J5 EXT VCO IN
R17
OPT
0603
R17
OPT
0603
R5 51.1R5 51.1
J9
3.3V J9
3.3V
J1
REF0 J1
REF0
E3
CP E3
CP
C6 0.1uF
0805
C6 0.1uF
0805
R2
4.99K
R2
4.99K
+
C1 35V
47uF
7361
+
C1 35V
47uF
7361
E15 V+VCXO
E15 V+VCXO
C38
100pF
C38
100pF
D1
LN1251C
D1
LN1251C
21
C21 0.1uF
0805
C21 0.1uF
0805 R23 OPTR23 OPT
CP_A
OPT 0603
CP_A
OPT 0603
CI2_P 0.1uF
1206
CI2_P 0.1uF
1206
C24
0.1uF
C24
0.1uF
C29
100pF
C29
100pF
E11 V+OA
E11 V+OA
C30
0.1uF
C30
0.1uF
CI1_A OPT
0603
CI1_A OPT
0603
C25
OPT
C25
OPT
A
B
U2
LT1678IS8
A
B
U2
LT1678IS8
1
OUTA
2
-INA
3
+INA
4
V-
5
+INB
6
-INB
7
OUTB
8
V+
E17 GND
E17 GND
R15
OPT
0603
R15
OPT
0603
CI1_P OPT
0603
CI1_P OPT
0603
R24 OPT
R24 OPT
C18
1.0uF
C18
1.0uF
J6 RF+
J6 RF+
U4
OPT
U4
OPT
VTUNE
1
EN
2
GND
3RFOUT 4
NC 5
VCC 6
J11 5V
J11 5V
L2
68nH
L2
68nH
C34 0.01uF
C34 0.01uF
+
C3
330uF
10V
+
C3
330uF
10V
C28 OPTC28 OPT
C35 0.1uF
0805
C35 0.1uF
0805
U3U3
GND 1
VTUNE 2
GND 3
GND 4
GND
5GND
6GND
7GND
8
GND
9RFOUT
10 GND
11 GND
12
GND 13
VCC 14
GND 15
GND 16
R13 OPT
0603
R13 OPT
0603
U1
LTC6945IUFD
U1
LTC6945IUFD
REFO
2
VCO- 15
STAT
3
MUTE
9
SCLK
5
V+D
8
SDO
7
RF+
12 RF-
11 GNDA
10
CS
4
VCO+ 16
GNDB 17
V+RF
13
V+REFO
1
BB
14
SDI
6GNDC 18
GNDD 19
GNDE 20
GNDF 21
V+VCO 22
GNDG 23
V+CP 24
CP 25
V+REF 26
REF+ 27
REF- 28
GND 29
C4
0.1uF
C4
0.1uF
J2
REF+ J2
REF+
E6
STATUS E6
STATUS
L3
68nH
L3
68nH
+
C19
35V
47uF
7361
+
C19
35V
47uF
7361
C26 100pFC26 100pF
C42
100pF
C42
100pF
CP_P
8200pF
0603
CP_P
8200pF
0603
L1
OPT
L1
OPT
E14 GND
E14 GND
R10
0
0603
R10
0
0603
C37
100pF
C37
100pF
E16 GND
E16 GND
J10
GND J10
GND
RZ_A OPT
0603
RZ_A OPT
0603
+
C7 20V
47uF
7343
+
C7 20V
47uF
7343
R4
330
R4
330
8
dc1649afa
DEMO MANUAL DC1649A
SCHEMATIC DIAGRAM
Note: The buffers shown on sheet 2 of 2 of the schematic are used to
protect the LTC6945 when communicating to it starts before powering it
up. There is no need for such circuitry if the SPI bus is not active before
powering up the LTC6945. The EEPROM is for identification and is not
needed to program the LTC6945.
A
A
B
B
C
C
D
D
E
E
4 4
3 3
22
11
DC590B SPI INTERFACE
0603
NOTE: EEPROM FOR BOARD IDENTIFICATION
3.3V
3.3V
3.3V
3.3V
CS
SCLK
SDI
SDO
SIZE
DATE:
.VER.ON CI
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
4
11/01/2011, 02:27 PM
22
ULTRALOW NOISE AND SPURIOUS INTEGER-N SYNTHESIZER
KIM T.
MICHEL A.
N/A
LTC6945IUFD
DEMO CIRCUIT 1649A
SIZE
DATE:
.VER.ON CI
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
4
11/01/2011, 02:27 PM
22
ULTRALOW NOISE AND SPURIOUS INTEGER-N SYNTHESIZER
KIM T.
MICHEL A.
N/A
LTC6945IUFD
DEMO CIRCUIT 1649A
SIZE
DATE:
.VER.ON CI
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
4
11/01/2011, 02:27 PM
22
ULTRALOW NOISE AND SPURIOUS INTEGER-N SYNTHESIZER
KIM T.
MICHEL A.
N/A
LTC6945IUFD
DEMO CIRCUIT 1649A
C44
0.1uF
C44
0.1uF
SDOSDO
R8
200K
R8
200K
R26
4.99K
R26
4.99K
EEPROM
ARRAY
U8
24LC025-I /ST
EEPROM
ARRAY
U8
24LC025-I /ST
SDA
5
VCC 8
A0
1A1
2A2
3
GND
4
WP
7SCL
6
SCLKSCLK
GND VCC
U5
NC7WZ17P6X
GND VCC
U5
NC7WZ17P6X
1 6
43
52
WPWP
R7
200K
R7
200K
R27
4.99K
R27
4.99K
GND
DIR
VCC(A) VCC(B)
U7
74LVC1T45GW
GND
DIR
VCC(A) VCC(B)
U7
74LVC1T45GW
1 6
43
52
R22 100R22 100
SDISDI
V+DIGV+DIG CSCS
C39
0.1uF
C39
0.1uF
C41 0.1uFC41 0.1uF
R9
0
R9
0
R25
4.99K
R25
4.99K
GND VCC
U6
NC7WZ17P6X
GND VCC
U6
NC7WZ17P6X
1 6
43
52
R21
100
R21
100
C36
0.1uF
C36
0.1uF
EEGNDEEGND
C43
0.1uF
C43
0.1uF
R12
100
R12
100
R18
200K
R18
200K
J8
HD2X7-079-MOLEX
J8
HD2X7-079-MOLEX
MOSI/SDA 7
EESDA 9
V+ 1
5V 2
CS 6
SCK/SCL 4
EEVCC 10
MISO 5
EESCL 11
EEGND 12
AUX 14
GND
3GND
13 GND
8
R19
200K
R19
200K
9
dc1649afa
DEMO MANUAL DC1649A
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
LAYOUT TOP LAYER
The top metal layer of DC1649A is shown here as an example of good PCB layout for the LTC6945.
10
dc1649afa
DEMO MANUAL DC1649A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2011
LT 0112 REV A • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims
arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and
observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC applica-
tion engineer.
Mailing Address:
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1630 McCarthy Blvd.
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Copyright © 2004, Linear Technology Corporation
